This shop allows you to transmute different shard components (tattered sapphire chunk, small amber rubble, etc). It is a convenient way to accumulate a particular crafting component in order to forge level 50 epics.

In order to discover the Essence Pool, a player has to:

Defeat Fear of the Dark fight 4, and receive a Vital Force, which is rewarded if you win the fight after triggering Tainted Siphon. This is apparently done if the Succubus uses Harvest while you're under the effect of an Abomination and Purifying Larva.Gather in Gaea's Dawn.